RFR: 8315066: Add unsigned bounds and known bits to TypeInt/Long [v7]

[Quan Anh Mai]

On Tue, 3 Sep 2024 13:33:21 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> src/hotspot/share/opto/type.hpp line 604:
>> 
>>> 602:   const jint _lo, _hi;       // Lower bound, upper bound in the signed domain
>>> 603:   const juint _ulo, _uhi;    // Lower bound, upper bound in the unsigned domain
>>> 604:   const juint _zeros, _ones; // Bits that are known to be 0 or 1
>> 
>> It would have been nice to have some sort of `Range` and `KnownBits` class... not sure how feasible this is, especially since `_lo` and `_hi` are already used all over the place...
>
> Can you explain the semantics of the combination of these? Each of these defines a subset of the whole int-range. Is the resulting type the intersection of all of these three?

That's what I thought too, but considering they are constants I think exposing them directly is fine. I have added explanation regarding the meaning of these constraints.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17508#discussion_r1742648488